This invention relates to a method and apparatus for interconnecting electrical circuit elements. More particularly, this invention relates to a new and improved solderless connector and method of using the same for establishing electrical contact between a flexible circuit and another circuit device utilizing relative motion therebetween to wipe away any debris or other foreign matter (i.e., corrosive films) which may adversely affect electrical contact.
Conventional methods of interconnecting electrical or electronic circuit components consist of the use of separate connector structures and/or soldering terminals on the components to conductors which deliver current to or from the components. While generally suitable for its intended purposes, interconnecting electrical components via separate connector structures does suffer from certain drawbacks and deficiencies including high manufacturing and purchasing costs as well as increased labor time and costs during installation and connection. Similarly, soldering terminals is undesirable as the substrate which supports an exposed terminal must be able to withstand relatively high temperatures with no adverse effects. Also, soldering connections can be time consuming and therefore be labor intensive and expensive. Another problem with soldered connections is the relative difficulty in disconnecting a soldered terminal during repairs and manufacturing.
In some applications it has been found desirable to replace the use of separate connecting structures and/or soldering as a technique for use in establishing connections to flexible and other circuits. In these applications, the requisite electrical contact may be established by mechanically pressing the terminal portions of the circuit against terminal pads on the connector, device or another circuit. Such prior art pressure connections are customarily made with the aid of a solid resilient pressure applicator, such as an elastomeric member, which is placed in compression to bias at least one of the components to be electrically interconnected toward the other component to hold the terminal portions thereof in electrical contact. Such a solderless connection system is disclosed in U.S. Pat. No. 4,468,074, assigned to the assignee hereof and incorporated herein by reference.
U.S. Pat. No. 4,468,074 discloses an apparatus wherein contact portions of a first array of conductive elements are urged against mating contacts of a second array of conductive elements by a pressure applicator comprising a resilient open-celled plastic material thereby establishing and maintaining an electrical connection therebetween. The use of such an open-celled resilient material permits a plurality of closely spaced exposed electrical conductors on or extending from a pair of substrates to be aligned and thereafter reliably pressed together; with the electrical connections being established by a requisite contact pressure applied to the substrates. The solderless connector of U.S. Pat. No. 4,468,074 may be employed to interconnect flexible circuits; to connect flexible circuits to circuits on rigid substrates; to establish connections between the leads extending from integrated circuit in a circuit pattern on a flexible or rigid circuit board; and in other applications.
It is well known that conventional electrical connector devices, such as of the male/female type, utilize mutual or relative sliding motion during the connecting process. This relative motion between the cooperating male and female connectors is desirable as it acts to "wipe" away any debris or foreign matter on the connectors. Such debris may adversely effect electrical contact. While suitable for its intended purposes, the solderless connector of U.S. Pat. No. 4,468,074 will not necessarily provide such relative motion between the flexible circuit and other circuit devices which are to be interconnected. This is because the circuit devices are interconnected when one device is brought down and disposed on another device thereby precluding any lateral movement which would act to wipe away undesirable foreign matter. Consequently, dirt, debris and other foreign matter may still be present on the respective electrical contacts subsequent to interconnection, which may lead to unreliable contacting.
Another area of concern with the "non-wiping" solderless connectors of the type disclosed in U.S. Pat. No. 4,468,074 is the open aging of the circuits before assembly. During exposure to the normal levels of corrosive gases common in air, the metal contact surfaces can corrode, reducing the electrical performance when assembled. As mentioned hereinabove, a typical method for improving the performance of connectors is to provide for a sliding motion between the contacts as they are mated. This sliding action breaks through the nonconductive corrosion layers that may have formed and thus improves the electrical performance of the connector.